1. Field of the Invention
The present invention relates to a voltage adjusting circuit for a motorcycle including an electrical component having an over-voltage protecting circuit and another electrical component having no over-voltage protecting circuit.
2. Description of Related Art
Conventionally, as shown in FIGS. 4 and 5, a power supply device for a vehicle such as a motorcycle includes a generator 101, a power supply control section (rectifier/regulator) 102 for rectifying electricity outputted from generator 101 and for regulating voltage thereof and a battery 103 detachably connected to power supply control section 102. A first electrical component, for example, a CDI unit 104 having an over-voltage protecting circuit 107 and a functional circuit 108, and a second electrical component having no over-voltage protecting circuit, for example, a tail light unit having an LED tail light 105, LED stop light 109 and a stop switch 106 are connected to battery 103. In this power supply device, generator 101 generates electric power and power supply control section 102 rectifies electricity and regulates voltage to supply the power, as shown in FIG. 5(a), to CDI unit 104 and the tail light unit while charging battery 103. When stop switch 106 closes because a rider operates a brake lever or pedal (not shown), LED stop light 109 is turned on.
In some situations, the engine is started with a kick starter with battery 103 removed, such as when weight reduction is required as used for races, or when battery 103 cannot be exchanged for a new one due to economical reasons in regions such as Southeast Asia. If battery 103 is thus removed, power supply control section 102 directly supplies power to CDI unit 104, LED tail light 105 and so forth without any charge function since battery 103 is removed, as shown in FIG. 5(b).
As a device relating to this kind of conventional art, JP-A-Hei 9-324732 (pages 2 and 3, FIG. 1) proposes an ignition control device that stops power supply to the battery and load devices when a supply voltage from a generator is lower than a preset value at a moment of engine ignition. If the battery malfunctions, sufficient ignition voltage is supplied only by a kick starter.
JP-A-2004-350441 (pages 4 and 5, FIG. 1) proposes a power supply circuit that charges a battery using a first coil and supplies the electric power necessary for engine control loads using only a second coil. Under an insufficient charge condition of the battery, sufficient electric power is supplied to the engine control loads only by a kick starter.
JP-B-3210101 (page 2, FIG. 2) proposes a constant voltage circuit for a magnet type AC generator that has an over-voltage preventing circuit that prevents an over-voltage output of a magnet type AC generator from being applied to loads such as electronic equipment.
JP-B-3660456 (page 3, FIG. 1) proposes a voltage adjusting circuit for a motorcycle-use generator that has means for preventing an over-voltage from being applied to loads connected to battery terminals in parallel to a battery even in situations such as when the battery accidentally comes off.
However, in the conventional art shown in FIGS. 4 and 5 and described above, if battery 103 is removed so that the motorcycle is used without the charge function, the regulation can delay because of the characteristic of power control section 102 and over-voltage can be applied to CDI unit 104, LED tail light 105 and so forth. Thus, the second electrical component, i.e., the tail light unit including LED tail light 105 and LED stop light 109, which has no over-voltage protecting circuit, can be damaged. LED parts such as LED tail light 105 in particular are weak against over-voltage and easily damaged. Similarly, JP-A-Hei 9-324732 and JP-A-2004-350441 do not assume that the motorcycle is used with the battery removed and thus the same problem can arise.
The over-voltage preventing circuits of JP-B-3210101 and JP-B-3660456 are formed with thyristors, resistors and capacitors. Thus, these circuits have the disadvantages of increased number of parts and costs.